Rapid diagnostic test device by driven flow technology

ABSTRACT

A rapid diagnostic test device uses driven flow technology to significantly expedite the testing time of a sample. The rapid diagnostic test device can be used to analyze liquids, such as some body fluids, by using labeled molecular affinity binding, such as immunochromatography. The test device can detect an analyte, such as an antibody or antigen, which may indicate a particular condition, the presence of a particular drug, or the like. The device includes a top and bottom that combine to form a fluid channel through which a fluid is forced from a fluid collector. A press pad in the device may press against a press pad on a test strip to accelerate chemical mixtures to flow from the conjugate color pad of the test strip toward fixed sites along the strip from which readings are taken.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One or more embodiments of the invention relate generally to apparatusfor analyzing liquids, such as body fluids, using labeled molecularaffinity binding, such as immunochromatography. More particularly, theinvention relates to strip test apparatus for detecting an analyte, suchas an antibody or antigen, which may indicate a particular condition.

2. Description of Prior Art and Related Information

The following background information may present examples of specificaspects of the prior art (e.g., without limitation, approaches, facts,or common wisdom) that, while expected to be helpful to further educatethe reader as to additional aspects of the prior art, is not to beconstrued as limiting the present invention, or any embodiments thereof,to anything stated or implied therein or inferred thereupon.

Labeled molecular affinity binding, such as immunochromatographicassays, have existed for decades and have proven to be an inexpensiveway to screen for various conditions, such as abused drugs, and otherconditions, such as pregnancy and cancer, or for single or multiplepathogenic conditions, such as HIV infection.

In the point-of-care test (POCT) setting, immunochromatographic assaysare typically conducted using lateral flow strip technology as describedin May et al., U.S. Pat. No. 5,656,503, incorporated herein byreference. With lateral flow devices, antibodies are movably supportedon a solid support, such as a porous pad. Antigen derivatives aredeposited as immobilized indicator lines downstream of the antibodies,whereby the target antigens in a fluid sample flow laterally as a liquidmatrix by capillary action through the solid support. The antibodies arenormally colored for visual indication. The fluid sample carries theantibodies downstream towards the indicator lines of immobilized antigenderivatives while a reaction takes place between the target antigens andthe antibodies. Any antibodies that have not reacted with the antigen inthe sample bind to the antigen derivatives at the indicator lines. Whenlittle or no target antigen is present in the sample, most or all of thecolored antibodies are carried downstream to the indicator lines of theimmobilized antigen derivatives. At the immobilized antigen derivatives,the colored antibodies bind together with the antigen derivatives insuch concentrations that the colorant of the antibodies becomes readilyvisible. It is also known that the antigen derivatives' and theantibodies' roles can be interchanged. That is, the antigen derivativescan be labeled with colorant and movably placed in the solid supportwhile the antibodies are placed as immobilized deposited indicator linesdownstream.

Unfortunately, although they can be inexpensive and simple-to-use,depending on the type of condition being detected, these tests typicallytake from about 5 to 20 minutes to complete and provide a typicalaccuracy of between 75% and 95%, falling short of the 99% or aboveaccuracy generally considered to be necessary for a confirmatory test.Moreover, these conventional tests provide no objective measure of aquantitative result, such as the concentration of a given drug presentin the liquid being tested.

The reasons for the insufficient accuracy in many rapid in vitrodiagnostic (IVD) test devices are primarily due to their current lack ofoverall higher sensitivity and specificity. Different samples maycontain chemicals or particles which inhibit the rapid and well mixedliquid flow or otherwise interfere with one or both of the first andsecond affinity binding reactions.

Other prior devices have attempted to enhance sensitivity or specificityby pretreating various parts of the device with reaction or flowenhancing reagents, pH conditioning chemicals, or even non-specificadhesive blocking molecules which will “block-out” non-analyte moleculeswhich might cause non-specific adhesion, or otherwise compete with theanalyte in question for specific binding members, especially in thereaction zones region of the strip. These attempts have met with limitedsuccess in some types of testing, but do not provide the desiredaccuracy in many others. Also, pretreatment with two or more of theabove pretreatments exacerbates the difficulties in obtaining uniformmanufacturing due to potential incompatibilities between thepretreatment chemicals. For example, the pH conditioner might disruptthe effectiveness of the non-specific blocking member molecules.Moreover, the manufacturing step of pretreating with a secondpretreatment chemical can dislodge some of the first pretreatmentchemical.

Further, lot-to-lot variation in the manufacture of many IVD testdevices can often lead to ambiguous results, such as false negatives aswell as weak false positives, so-called “ghostlines” or “phantom lines”.False negatives typically occur when non-specific molecules interferewith the first and/or second affinity binding actions. It has been foundthat non-analyte molecules can clump together in liquid samples that arenot well mixed so that they temporarily prevent access between analytesand binding members. Even temporary interference in past devices canprevent an adequate number of labeled analyte complexes and/orultimately immuno-sandwich complexes from forming. In this way, if anon-analyte molecule or clump of molecules blocks access betweenanalytes and binding members for only a few seconds, it may be enough toinduce a false negative result. Further, clumps of non-analyte moleculescan carry an overabundance of the labeled mobilizable binding members tothe second affinity binding site to generate a false positive result.

Lateral flow devices are useful due to their low cost and ease of use.However, prior lateral flow devices suffer from low accuracy andrelatively long test wait times as detailed above. This is especiallytrue for saliva testing because of the low concentrations of analytespresent. Current lateral flow strips cannot provide the necessarysensitivity and specificity within the time normally allotted to atypical law enforcement action such as a traffic stop.

The low accuracy can be due to a number of problems unique to lateralflow-type tests. First, there is often uneven movement of theimmunoparticles within the nitrocellulose membrane. Smaller, non-analytemolecules mix together with the larger analyte molecules and compete forsites, often preventing the larger molecules from reacting in thedesired fashion.

Therefore, there is a need to improve the accuracy of rapid IVD testdevices so that rapid, inexpensive, easily conducted and quantitativeimmunological testing becomes a reality.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a device for testing aliquid sample for the concentration of at least one analyte, comprisinga top member; a bottom member connecting to the top member forming aninternal cavity therein; a fluid directing channel formed in theinternal cavity; an inlet formed in a first end of the device, the inletfluidly communicating with the fluid directing channel; a press padformed in the top member, the press pad configured to press against aconjugate color pad of a test strip disposed within the internal cavity;and a cap fitting over the first end of the device, the cap configuredto press against a fluid collector having the liquid sample disposedtherein, thereby driving the fluid sample into the fluid directingchannel.

Embodiments of the present invention further provide a test system fortesting a liquid sample for the concentration of at least one analytecomprising at least one test strip comprising a conjugate color padincluding a source of mobilizable labeled first affinity binding membersbindable to the analyte; a liquid permeable reaction region including atleast one strip line including immobilized second affinity capturebinding members bindable to said analyte; and a strip press pad disposedover the conjugate color pad; and a test device comprising a top member;a bottom member connecting to the top member forming an internal cavitytherein; a fluid directing channel formed in the internal cavitycontaining the test strip; an inlet formed in a first end of the device,the inlet fluidly communicating with the fluid directing channel; apress pad formed in the top member, the press pad configured to pressagainst the strip press pad and the conjugate color pad of the teststrip; and a cap fitting over the first end of the device, the capconfigured to press against a fluid collector having the liquid sampledisposed therein, thereby driving the fluid sample into the fluiddirecting channel.

Embodiments of the present invention also provide a method for testingfor an analyte in a sample, comprising disposing at least one test stripinto an internal cavity formed between a top member and a bottom memberof a test device; sliding a cap onto a first end of the test device tocompress a fluid collector to cause the sample to be expelled from thefluid collector into a fluid directing channel formed in the internalcavity; directing the fluid from the fluid directing channel to aconjugate color pad of the test strip, the conjugate color pad disposedon a press pad of the top member; and exerting an additional force onthe conjugate color pad of the test strip as the cap is slid furtheronto the first end of the test device.

In some embodiments, the results can be rapid qualitative/quantitativeresults with up to 99% accuracy.

In some embodiments, the structure of the rapid diagnostic test devicecauses a high speed, rapid flow of liquid out of a fluid collectortoward a reaction region of the test strip.

In some embodiments, there is provided a labeled molecular affinitybinding assay strip device having a source of mobilizable first affinitybinding members in the conjugate color pad and a number of fixed secondaffinity binding sites in the reaction region of the test strip, wherethe reaction region is visible through a result window of the testdevice.

In some embodiments, the diagnostic test device provides a morepredictable rate of uptake of labeled analytes at the strip lines inorder to provide a quantitative result.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention are illustrated as an exampleand are not limited by the figures of the accompanying drawings, inwhich like references may indicate similar elements.

FIG. 1 is a diagrammatical perspective view of an assay cartridgeaccording to an exemplary embodiment of the invention;

FIG. 2 is a diagrammatical cross-sectional side view of the assaycartridge of FIG. 1 taken along line 2-2 shown in the cap open position;

FIG. 3 is a diagrammatical cross-sectional side view of the assaycartridge of FIG. 2 taken along line 3-3 showing the strip-enclosingconstriction structure;

FIG. 4 is a diagrammatical cross-sectional side view of the strip ofFIG. 2;

FIG. 5 is a diagrammatical cross-sectional side view of the assaycartridge of FIG. 1 shown in the cap closed position;

FIG. 6 is a diagrammatical cross-sectional side view of the cartridge ofFIG. 1 showing progressive compression force components at various timesand position during cap emplacement;

FIG. 7 is a diagrammatical chart showing progressive compression forcecomponents at various times during cap emplacement;

FIG. 8 is a diagrammatical chart showing the relatively uniform flowmagnitude during a transition from primarily a compression driving forceto a siphoning driving force;

FIG. 9 is a diagrammatical cross-sectional side view of an alternateembodiment of a cap having a strip crumpling structure;

FIG. 10 is a diagrammatical cross-sectional side view of an alternateembodiment of a cartridge having a support shelf for supporting the freeend of the strip;

FIG. 11 is a diagrammatical cross-sectional side view of an alternateembodiment of a cap having an internal deflectable beam progressivecompression structure;

FIG. 12 is a diagrammatical cross-sectional side view of an alternateembodiment of a cap having an internal slider progressive compressionstructure;

FIG. 13 is a diagrammatical cross-sectional side view of an alternateembodiment of a cap having a pressurizing collapsible bulb progressivecompression structure;

FIG. 14 is a diagrammatical cross-sectional side view of the cartridgeof FIG. 1 loaded in a result reader;

FIG. 15 is a diagrammatical cross-sectional side view of an assaycartridge according to an alternate exemplary embodiment of theinvention having a light emitter enhanced reader;

FIG. 16 illustrates a partially transparent perspective view of a rapiddiagnostic test device, having three test strips and a fluid collectordisposed therein, in accordance with an embodiment of the presentinvention;

FIG. 17A illustrates a front perspective view of a top member of therapid diagnostic test device of FIG. 16;

FIG. 17B illustrates a front view of the top member of the rapiddiagnostic test device of FIG. 16;

FIG. 17C illustrates a side view of the top member of the rapiddiagnostic test device of FIG. 16;

FIG. 18A illustrates a front perspective view of a bottom member of therapid diagnostic test device of FIG. 16;

FIG. 18B illustrates a front view of the bottom member of the rapiddiagnostic test device of FIG. 16;

FIG. 18C illustrates a side view of the bottom member of the rapiddiagnostic test device of FIG. 16;

FIG. 19A illustrates a front perspective view of a cap member of therapid diagnostic test device of FIG. 16;

FIG. 19B illustrates a back view of the cap member of the rapiddiagnostic test device of FIG. 16;

FIG. 19C illustrates a front perspective view of a squeezing portion ofthe cap member of FIG. 19A;

FIG. 19D illustrates a back view of the squeezing portion of FIG. 19C;

FIG. 19E illustrates a partially cut-away side view of the squeezingportion of FIG. 19C;

FIG. 19F illustrates a side view of a specimen collection portion of thecap member of FIG. 19A;

FIG. 19G illustrates a front view of the specimen collection portion ofFIG. 19F;

FIG. 19H illustrates a partially cut-away side view of the specimencollection portion of FIG. 19F;

FIG. 19J illustrates a side view showing coupling of the squeezingportion of FIG. 19C with the specimen collection portion of FIG. 19F;

FIG. 20 illustrates a perspective view of an exemplary fluid collectorusable in the rapid diagnostic test device of FIG. 16;

FIG. 21 illustrates a partially transparent perspective view of therapid diagnostic test device of FIG. 16, without test strips or a fluidcollector and cap disposed therein;

FIG. 22 illustrates a perspective view of the top member of FIG. 17Awith a test strip disposed therein;

FIG. 23 illustrates a side view of an exemplary test strip,demonstrating fluid movement therealong; and

FIG. 24 illustrates a perspective view of the rapid diagnostic testdevice of FIG. 16 is use with its cap compressing a fluid collectoraccording to an exemplary embodiment of the present invention.

Unless otherwise indicated illustrations in the figures are notnecessarily drawn to scale.

The invention and its various embodiments can now be better understoodby turning to the following detailed description wherein illustratedembodiments are described. It is to be expressly understood that theillustrated embodiments are set forth as examples and not by way oflimitations on the invention as ultimately defined in the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS AND BEST MODE OFINVENTION

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items. As used herein, the singularforms “a,” “an,” and “the” are intended to include the plural forms aswell as the singular forms, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by onehaving ordinary skill in the art to which this invention belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

In describing the invention, it will be understood that a number oftechniques and steps are disclosed. Each of these has individual benefitand each can also be used in conjunction with one or more, or in somecases all, of the other disclosed techniques. Accordingly, for the sakeof clarity, this description will refrain from repeating every possiblecombination of the individual steps in an unnecessary fashion.Nevertheless, the specification and claims should be read with theunderstanding that such combinations are entirely within the scope ofthe invention and the claims.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be evident, however, toone skilled in the art that the present invention may be practicedwithout these specific details.

The present disclosure is to be considered as an exemplification of theinvention, and is not intended to limit the invention to the specificembodiments illustrated by the figures or description below.

As is well known to those skilled in the art, many carefulconsiderations and compromises typically must be made when designing forthe optimal configuration of a commercial implementation of any device,and in particular, the embodiments of the present invention. Acommercial implementation in accordance with the spirit and teachings ofthe present invention may be configured according to the needs of theparticular application, whereby any aspect(s), feature(s), function(s),result(s), component(s), approach(es), or step(s) of the teachingsrelated to any described embodiment of the present invention may besuitably omitted, included, adapted, mixed and matched, or improvedand/or optimized by those skilled in the art, using their average skillsand known techniques, to achieve the desired implementation thataddresses the needs of the particular application.

The instant embodiments are useful to rapidly determine the presence ofan analyte in a liquid sample at a concentration which confirms thecondition being tested. The sample can include, for example, bodyfluids, such as whole blood, serum, plasma, urine, spinal fluid,amniotic fluid, mucous, saliva, and the like, or other fluids used incertain food and environmental testing.

As used herein, the term “analyte” refers to a compound or compositionto be measured. The analyte can be any substance, such as an antigen orligand, for which there exists a naturally or genetically occurringspecific binding member, for instance, a binding molecule such as anantibody or receptor, and other molecules that exhibit the so-called“lock-in-key” pairing function.

Analytes also includes any antigenic substances, haptens, antibodies,and combinations thereof. The analyte can include a protein; a peptide;an amino acid; a ligand; a hormone; asteroid; a vitamin; a drug,including those administered for therapeutic purposes as well as thoseadministered for illicit purposes; a pathogen; and an exogeniousinfectious microbe, such as a bacterium, a virus, and metabolites of orantibodies to any of the above substances. The analyte can also comprisean antigenic marker or antibody or receptor.

The precise nature of a number of analytes, together with a number ofexamples thereof are disclosed in Litman, et al., U.S. Pat. No.4,299,916, issued Nov. 10, 1981; and Tom, et al., U.S. Pat. No.4,366,241, issued Dec. 28, 1982, each of which are herein incorporatedby reference in their entirety. Certain improved accuracy devices aredisclosed in U.S. Pat. No. 8,021,625 (Wang et al.), which isincorporated herein by reference in its entirety.

The signal provided to the user of the device is provided byaccumulation of a visually detectable label conjugated to a mobilizablebinding member such as a specific antibody and/or antigen; ligand and/orreceptor. This mobilizable binding member is sometimes referred to as a“binding member molecule”, “a first affinity binding member”, “labeledbinding member” or simply “conjugate”. In the instant embodiments,labels that produce a readily detectable signal are used. Thus, theinstant embodiments provide colored labels which permit visibledetection of the assay results without the addition of furthersubstances and/or without the aid of instrumentation. However, in someembodiments, instrumentation may be used to provide a comparative orquantitative representation of the concentration of analyte in thesample.

The test strips described in these embodiments can include regions orpads that may include a dry, porous material. By “porous” it is meantthat the matrix of material forming the porous structure allows liquidsto flow through it.

As used herein, the term “sample pad” or “fluid collector” means thepart of the assay device which is in direct contact with the liquidsample first during test operation, i.e., it receives the sample to betested for the analyte in question. The fluid collector may be made ofporous material, such as porous paper, cotton, cellulose, mixed fibers,glass fiber, polyester fiber, and the like.

The term “conjugate pad” or “conjugate color pad”, as used herein,refers to the part of the assay device which is in liquid flow contactwith the porous material of fluid collector. The contact can be anoverlap or end-to-end connection, such that the liquid sample canmigrate via wicking action or by surface tension-based forces such ascapillary forces from the fluid collector through the conjugate pad. Theconjugate pad comprises a porous material and a mobilizable labeledreagent that is capable of binding the analyte in question to form alabeled reagent-analyte complex which then migrates via liquid flow withthe liquid sample along the pad.

The term “mobilizable” as referred to herein means diffusively ornon-diffusively attached, or impregnated. The mobilizable reagents arecapable of dispersing with the liquid sample and carried by the liquidsample in the liquid flow.

In one exemplary embodiment, human immunodeficiency virus (“HIV”) in afluid specimen, such as saliva, is detected as a putative targetanalyte. Those skilled in the art will readily appreciate adaptation ofthese embodiments to detect other analytes indicative of otherpathogens, or pathogenic conditions in body, drugs of abuse (“DOA”),food or environmental fluid specimens, and the like.

Further the exemplary embodiments will be described in connection withan immunochromatographic assay based on antigen/antibody binding. Thoseskilled in the art will readily appreciate adaptation of theseembodiments to other types of molecular affinity binding-based tests.

Referring now to FIGS. 1-5, there is shown a diagrammatical illustrationof a labeled molecular affinity binding test device 1 including acartridge body 21 and a cap 22 made from a generally liquid impermeabledurable material such as injection molded plastic. The cartridge carriesin an internal cavity at least one test strip 23 containing thechemicals necessary to conduct the labeled molecular affinity bindingtest. The strip has an oblong backing 15 made from liquid impermeablematerial such as plastic extending the entire length of the strip sothat liquid can ride along the upper surface of the backing during itsflow. The internal cavity of the cartridge body is shaped anddimensioned to carry a first portion 17 of the strip including theconjugate pad 26 impregnated with a lyophized, mobilizable, firstaffinity binding member, such as an HIV antigen or antibody, conjugatedto a label such as colloidal gold, and a reaction region 27 includingone or more zones 28,29 impregnated with lyophized, immobilized, secondaffinity binder members intended to capture first affinity boundmolecules. Thus the first affinity binding members are initiallyseparated from the second affinity binding members.

The cap 22 can be shaped and dimensioned to engage the cartridge body,and have an internal chamber shaped and dimensioned to enclose a second,remainder portion 16 of the strip including the exposed end of thesample pad 25.

The device can be delivered in a pre-used condition where the strip hasbeen preloaded into the cartridge and the cap protectively placed overthe free end of the strip and held in place by a nib 45 on the cartridgeengaging a hole 46 in the cap.

To initiate a test, the user removes the cap 22 so that the device is inthe cap open position as shown in FIG. 1, and deposits a liquid sample24 upon the sample pad 25 at a distal exposed end of the strip 23. Thesample liquid then flows primarily through the forces of capillarity andgravity into a thickened, convexly-shaped conjugate pad 26. The liquidwill tend toward fully saturating the thickened conjugate pad before anysubstantial flow leaves the conjugate pad for the reaction region 27.

The thickened conjugate pad 26 is located beneath a compressionstructure 36 on the cartridge body 21. The compression structure can beformed by a cantilevered beam 38 having a fixed proximal end and adistal free end 42. The beam is allowed to deflect downwardly as itcomes into contact with the sloped surface of the ramp 32. The downwarddeflection is facilitated by a narrow isthmus of material 37 connectingthe fixed proximal end of the beam to the cartridge body. The isthmusacts as a relatively stiff mechanical hinge, providing predeterminedresistance to deflection which can be selected during manufacture byselecting the thickness of the isthmus. This helps the beam from beinginadvertently deflected prior to the directed intentional placement ofthe cap.

The user then replaces the cap 22 and forces it into the cap closed,test initiation position shown in FIG. 5. A second nib 45 engages thehole 46 on the cap to indicate that the cap has reached the closedposition. The sloped surface of the ramp 32 of the cap having an angle33 of between about 0 and 25 degrees progressively forces thecantilevered beam of the compression structure 36 downward as the capmoves toward the closed position. The beam presses against the top sideof the thickened conjugate pad 26 forcing liquid out of the pad due toan overpressure force an on downstream as indicated by the arrow 47toward the reaction region 27 carrying one or more result zones 28,29 ofimmobilized, second affinity binding members. The analyte moleculesalready bound to conjugated first affinity binding members can now bindto the immobilized members located in the zones and accumulate there insignificant numbers to indicate a test result through the observationwindow 19.

Liquid continues to flow into an absorbent reservoir pad 30 located atthe proximal end of the cartridge. An empty chamber 31 having an opening39 outside the cartridge at the proximal end of the cartridge relievesany buildup of backwards pressure against the flow of liquid into thereservoir. Optionally, the chamber can have an opening to the outside toensure no buildup of pressure occurs during the movement of liquidthrough the device. Optionally, an amount of desiccant can be placed inthe chamber to keep the strip dry until use.

As shown in FIG. 3, it is important to note that the reaction region 27part of the strip 23 is surrounded on its perimeter 35 by astrip-enclosing constriction structure formed by the close proximity ofthe cartridge body 21 so that once liquid has reached the reservoir 30,additional liquid is drawn out of the conjugate pad by siphoning forcesin combination with the other forces. This siphoning force takes overfor a diminishing compression force as the beam reaches its fulldeflection, so that the pressure of the liquid flow is maintained. Thesample pad, conjugate pad, reaction region, and absorption pad are indirect liquid flow contact with each other such that the direction ofliquid flow in the test device is from the sample pad to conjugate padto reaction region and ultimately to the absorption pad. Thus, theliquid sample is driven through the strip by a force which is thecombination of forces due primarily to compression forces and siphoning,and potentially gravity.

As shown schematically in FIG. 6 and graphically in FIG. 7, thecompression force 70 is applied progressively along the downstreamdirection 47 of liquid flow during cap emplacement onto the cartridgebody. Before the cap 22 contacts the cartridge body 21 at T0 there is nocompression force applied. At time T1, when the cap 22 has been movedmore proximally, the deflecting the beam 38 generates a compressionforce having a force component Fd applied to a distal point on theconjugate pad 26 that is greater than zero while the force component Fpat a proximal point remains zero. At time T2, as the compressionstructure beam 38 becomes more deflected, a compression force is appliedhaving a force component Fp applied to the proximal point on theconjugate pad 26 that is greater than zero, while the force component Fdat the distal point is greater than Fp. At time T3 when the compressionstructure beam 38 is fully deflected and the cap 22 is in the closedposition, a compression force is applied having a force component Fp andFd at their maximums, where distal point Fd remains greater than Fp.

As graphically shown in FIG. 8, the magnitude of the flow through thereaction region over time 80 is at T0 first attributable to surfacetension forces (also known as capillarity) alone while the cap remainsin the open position. Then as the cap is replaced from T1 to T3 theoverall flow through the reaction region is primarily attributable tothe compression force. After the cap has been replaced, the flowattributable to the compression force drops off, while the flowattributable to siphoning increases. By T4, the flow is almost entirelydriven by siphoning. In this way, the magnitude of the flow through thereaction region is more uniform over a longer period of time because theflow occurs primarily due to overpressure forces during a first timeperiod, and primarily due to siphoning forces during a second,subsequent time period.

Referring now to FIG. 9 there is shown an alternate embodiment of theprogressive compression structure. The cap 62 similar to the device ofFIG. 1 includes an additional angled bulkhead 63 for directing thedistal end 64 of the strip 65 toward a receptacle 66 as the cap is movedfrom the open position to the closed position. Once the distal end ofthe strip is trapped in the receptacle, the bulkhead forces the end ofthe strip crumple upon itself into corrugations 67 which serve to driveliquid out of the sample pad and downstream into the conjugate pad. Thisadded source of liquid can further pressurize the liquid exiting theconjugate pad. The strip crumpling structure can be used alone or incombination with other structures for driving liquid in a downstreamdirection on the strip.

Referring now to FIG. 10 there is shown an alternate embodiment of thecartridge body 91 having a support shelf 92 supporting the distal end 93of the strip 94. Further, the top of the conjugate pad 95 is exposed.This cartridge body can be used with various progressive compressionstructures as detailed below.

In FIG. 11 there is shown an alternate embodiment of the progressivecompression structure 101 having a deflectable beam 110 having a fixedend 111 secured to the distal end 112 of the cap 113. Once the cap isplace in a closed position upon the cartridge body 91, the beam islocated above the sample pad and the conjugate pad. Upon depressing apush button 114, the beam is deflected against the sample pad and theconjugate pad in a progressive compression action which forces liquidfrom the sample pad and conjugate pad toward the reaction region.

In FIG. 12 there is shown an alternate embodiment of the progressivecompression structure 102 having a moveable slider 120 mounted within atrack 121 on the cap 122. The slider has a shoe 123 which bears againstthe sample pad once the cap is placed in a closed position upon thecartridge body 91. Upon pushing the button of the slider proximallytoward the proximal end of the cartridge, the shoe progressively impartsa compression force along the sample pad and then the conjugate pad ofthe strip which forces liquid from the sample pad and conjugate padtoward the reaction region. A protective, friction-reducing bib 124 madefrom a flexible liquid resistant material such as a pliable plasticseparates the bottom of the shoe from the strip and facilitates thesliding of the shoe over the strip.

In FIG. 13 there is shown an alternate embodiment of the progressivecompression structure 103 having a pressure inducing collapsible bulb130 made from resiliently flexible, air-tight material such asrubberized plastic formed into the cap 131. Once the cap is placed in aclosed position upon the cartridge body 91, an air-tight seal is formedwith the cartridge body over the end of the strip and the air-filledchamber 132 inside the bulb is open to the end of the strip. The bulbcan then be collapsed under the force of a person's finger and thumb toincrease the pressure within the chamber imparting a force progressivelyfrom the exposed end of the strip at the sample pad and then on to theconjugate pad which forces liquid from the sample pad and conjugate padtoward the reaction region.

The application of the progressive compression force has a dramaticeffect on micro-flow dynamics in the strip. In general, the result is amore rapid and thorough mixing of the sample with the reaction moleculesso that a greater and more rapid opportunity is provided for the firstand second bindings to occur, and a more even liquid front reaching thesites of second affinity binding.

More specifically, the pressurized movement of the liquid sample throughthe porous material of the conjugate pad 26 causes the liquid front toseparate into branches and rejoin from different directions as itcourses around the material fibers. The convergence from differentdirections causes a mixing across the liquid front and the liquid thatfollows as the sample flows downstream 47. This enhanced mixing cancause the break-up of clumps of non-analyte molecules which may carrymobilizable labeled binding members, to reduce false positives. Themixing also reduces the differences in the concentrations of non-analytemolecules and labeled analyte complexes so that they are spread moreevenly.

In addition, prior to the compression force being applied, the liquidhas tended to saturate the thickened conjugate pad 26. Once thecompression force is applied, the liquid forcefully exits the conjugatepad into a narrower cross-section of the strip entering the reactionregion 27. This action increases the velocity of the liquid in thereaction region according to the Bernoulli Principle, reducing itspressure causing further mixing and leading to a more evenly mixedliquid front. Further, because of the thickened shape of the conjugatepad, the direction of flow of the liquid exiting the upper parts of theconjugate pad must make a downward turn 48 to flow into the reactionregion. This change in direction also serves to better mix the liquid.

Once the liquid front reaches the reaction region 27, the concentrationshave superior uniformity across the width of the strip which leadsdirectly to giving the labeled analyte complexes a greater opportunityto form the second affinity binding at the immobilized sites in theresult zones 28,29 and thereby increasing the overall sensitivity andspecificity of the test and reducing false negatives.

Within 10 seconds or less a predicable amount of reactable sample liquidhas passed through the conjugate pad and through the reaction region.This amount is about 100 to 300 microliter. As shown in FIG. 14, anautomated reader 18 can read by reflected light the result of the testand generate an electronic signal that can be forwarded to a computerfor further analysis and distribution to a data network. The computercan be implemented using a mobile phone device running the appropriatesoftware, for example. By being able to predict the amount of reactedsample that has passed through the reaction region, the intensity of thelines in the result zones can indicate a quantitative result. In otherwords, the automated reader can the detect not just whether a line hasappeared or not, but rather the intensity of the line, and digitize thatintensity reading. That reading corresponds directly with the amount ofanalyte present in the sample, providing a digitized quantitativeresult.

Alternately, as shown in FIG. 15, a device 51 can include a secondwindow 55 located beneath the result zones 56,57 so that a light emitter54 can shine light through the reaction region to be received by thereader 52 and the mobile phone analysis tool 53. Indeed, the entirecartridge can be made from translucent material.

According to an exemplary embodiment of a driven flow test device andreferring to FIG. 16, a rapid diagnostic test device 210, also referredto as simply test device 210, can include a top member 212 connected toa bottom member 214. One or more test strips 270 (three such test strips270 are shown in FIG. 16) may be disposed inside the test device 210between the top member 212 and the bottom member 214. A result window216 may be formed in at least one of the top member 212 and the bottommember 214 to allow a user to view the results of the test. As describedin greater detail below, the result window 216 can align with one ormore strip lines 274 (see FIG. 22) of the test strip 270.

A cap 218 may be slidably and removably disposed on one end of the testdevice 210. During use of the test device 210 to test a sample for ananalyte, the cap 218 is slid onto the end of the test device 210 and afluid collector 220, disposed within and extending from an inlet 260(see FIG. 21) of the test device 210, may be compressed to drive samplefluid onto and through the test strips 270, as described in greaterdetail below.

Referring now to FIGS. 17A, 17B and 17C, the top member 212 is shown indetail, without the bottom member 214 attached thereto. The top member222 can include a press pad 222 adapted to align with a conjugate colorpad 272 and strip press pad 278 of the test strip 270 (see FIG. 23). Afluid directing channel 224 is formed at one end of the top member 212.The fluid directing channel 224 is bounded on each side by side walls226 and terminates at the press pad 222. As discussed below, the fluiddirecting channel 224 may direct fluid from the fluid collector 220toward the conjugate color pad 272 of the test strip 270.

A top member result window 216A may be disposed in the top member 212.The top member result window 216A may be formed from a clear or opaquematerial, allowing a user to read results on the test strip 270 disposedwithin the test device 210.

Referring to FIGS. 18A, 18B and 18C, the bottom member 214 is shown indetail, without the top member 212 attached thereto. The bottom member214 includes a fluid directing channel 238 that aligns with the fluiddirecting channel 224 of the top member 212 to receive the fluidcollector 220 therein. Like the fluid directing channel 224 of the topmember 212, the fluid directing channel 238 of the bottom member 214 canbe bounded on each side by side walls 237.

A plurality of side bars 224 can define strip slots 235 for disposingthe test strips 270. The side bars 224 may be disposed adjacent to theinner terminus of the fluid directing channel 238. Similarly, aplurality of upper side bars 232 may be disposed on an opposite end(opposite the plurality of side bars 224) of the bottom member. Theplurality of upper side bars 232 may align with the plurality of sidebars 224 so that the test strips 270 are disposed within the test device210 adjacent to each other and generally parallel with each other, asshown in FIG. 16.

The bottom member 214 can include a plurality of secure/alignment holes239 to receive secure/alignment pins 229 of the top member 212 when thetop member 212 is attached to the bottom member 214. Side clips 236 maybe disposed on each side of the bottom member 214. The side clips 236may fit into connection notches 228 of the top member 212 to removablysecure the top member 212 to the bottom member 214. Of course, othermethods of connecting the top member 212 to the bottom member 214 arecontemplated within the scope of the present invention. Such connectionsmay include friction fit, fasteners, twist lock connectors, or the like.

Referring to FIGS. 19A and 19B, the cap 218 is shown in greater detail.The cap 218 may be configured to fit onto the end of the test device 210as shown in FIG. 16. A top notch plate 242 and a bottom notch plate 244may be formed in the cap 218. The notch plates 242, 244 may be disposeddirectly opposite each other, as shown, or, in some embodiments, may beoffset. The notch plates 242, 244 may be formed in various shapes andsizes and typically protrude into an interior region of the cap 218 topress against the fluid collector 220, as discussed in greater detailbelow. In some embodiments, the cap 218 may sealingly engage the topmember 212 and the bottom member 214 such that excess fluid in the cap218 may not leak out while the cap is disposed on the test device 210.

In some embodiments, the cap 218 may be formed from a specimen retentionportion 320 and a fluid collector squeezing portion 300 (also referredto simply as squeezing portion 300). FIGS. 19C to 19E show views of thesqueezing portion 300. The squeezing portion 300 can include an outerbody 302 having a fluid collector opening 304 at one end thereof. Sidewalls 306 may be disposed inside of the opening 304 to provide a stopagainst the device 210. This stopping action can help assure the userthat the cap 218 is properly placed onto the device 210 before squeezingthe squeezing portion 300.

A back side 310 of the squeezing portion 300 may be solid or fluidimpermeable, except for a specimen collection opening 308 formedtherein. When the squeezing portion 300 is squeezed, the specimen may bedelivered to the device 210, as described below, while excess fluid maypass through the specimen collection opening 308 and into the specimenretention portion 320 of the cap 218. An interior of the cap 218 may besloped on one or both sides to direct fluid to the device 210 and limitthe fluid flow through the specimen collection opening 308. A ramp 312on both sides of the cap 218 is shown in FIG. 19E. The squeezing portion320 may be formed at least partially from a resiliently deformablematerial that may be squeezed together to reduce the volume inside thefluid collector opening 304.

Referring now to FIGS. 19F through 19J, the specimen retention portion320 is shown in greater detail. The specimen retention portion 320 mayinclude a solid front panel 324 that aligns with the back side 310 ofthe squeezing portion 300. A retention portion opening 326 may be formedin the front panel 324 of the specimen retention portion 320. Theretention portion opening 326 may align with the specimen collectionopening 308 of the squeezing portion when the cap 218 is assembled asshown in FIG. 19A. In some embodiments, the retention portion opening326 may be formed as a one-way valve, where specimen is permitted intothe specimen retention portion 320 when the specimen retention portion320 is attached to the squeezing portion 300, but, when detached, theretention portion opening 326 may automatically seal to prevent specimenfrom spilling from the specimen retention portion 320.

Alignment pins 322 may coordinate with alignment pins 314 of thesqueezing portion (see FIG. 19E) when the squeezing portion 300 isassembled with the specimen retention portion 320 as shown in FIG. 19J.

In some embodiments, the specimen retention portion 320 may be formedseparately from the squeezing portion 300. In other embodiments, the cap218, including the specimen retention portion 320 and the squeezingportion 300 may be formed integrally, as a single component.

The fluid collector 220, as shown in FIG. 20, may be formed of variousmaterials and shapes, as described above, that can collect and contain aliquid sample. Typically, the fluid collector 220 is formed from aporous, deformable material such that, when depressed by the cap 218,the fluid collector 220 may release at least a portion of the fluid(sample) contained therein toward the conjugate color pad 272 of thetest strip 270.

Referring now to FIGS. 21 through 24, the use of the test device 210will be described according to an exemplary embodiment of the presentinvention.

A sample, such as a body fluid, can be collected on the fluid collector220. In one embodiment, saliva may be collected from a person onto thefluid collector 220. In some embodiments, the fluid collector 220 may bealready held in the inlet 260 of the test device 210 while the sample isobtained. In other embodiments, the sample may be placed onto the fluidcollector 220 and then the fluid collector 220 may be placed into theinlet 260 of the test device 210. In still other embodiments, the fluidcollector 220 may only press against the inlet 260 of the test device210 and compression of the fluid collector 220 may drive fluid into thefluid directing channel 224, 238. Compression of the fluid collector 220may be achieved by various manners. In some embodiments, sliding the cap218 onto the device 210 may compress the fluid collector 220. In otherembodiments, the squeezing portion 300 of the cap 218 may be squeezed todrive fluid out of the fluid collector 220 and into the inlet 260 of thetest device 210.

One or more test strips 270 may be disposed in the test device 210. Thetest strips 270 can include a substrate 276 onto which a porous material274 is disposed. Each test strip 270 may include a plurality of striplines 274 that may indicate the presence or absence of a particularsubstance. In other words, each test strip 270 may test for a pluralityof substances. For example, each test strip 270 may be capable oftesting for five substances. Therefore, when the test device 210 isdesigned to hold three test strips 270, as shown, such a test device maybe capable of testing for 15 substances.

The conjugate color pad 272 may be disposed below the press pad 222 ofthe top member 212. In some embodiments, a strip press pad 278 may beformed as part of the test strip 270. As the cap 218 is slid onto thetest device 210, the cap 218 may squeeze the top member 212 toward thebottom member 214, causing the press pad 222 of the top member to pressdownward onto the strip press pad 278 and/or the conjugate color pad272.

The sample collected in the fluid collector 220 may be forced out of thefluid collector 220 by sliding the cap 218 onto the end of the testdevice 210, where the notch plates 242, 244 (see also, FIGS. 19A and19B) compress the fluid collector 220 as shown in FIG. 24. The sample isforced to flow into the fluid directing channel 224, 238 toward theconjugate color pad 272 (see FIGS. 18A, 18B and 22). Excess sample fromthe fluid collector 220 may be reserved on the bottom of the cap 218 forfurther testing needs.

The strip press pad 278 may play the role as an auxiliary function todrive chemical mixtures, pre-impregnated on the conjugate color pad 272,out of the conjugate color pad 272 completely. The conjugate color pad272 provides a source of mobilizable first affinity binding members 280which may bind with substances in the sample to form a reactioncomponent 282. The strip lines 274 of the test strip 270 can includefixed second affinity binding sites that may react with the reactioncomponent 282 to provide a readable output, indicating the presence orabsence of the substance.

The driven flow mechanism of the test device 210 can significantlyexpedite testing time to about one minute, for example, which istypically about 5 to 20 times faster than conventional rapid testdevices.

Because the strip press pad 278 and the press pad 222 of the top member212 help ensures that the chemical mixtures may be completely driven outof the conjugate color pad 272, the test device 210 of the presentinvention may be used to provide a quantitative result. For quantitativemeasurements, in some embodiments, the result window 216 may be formedin both the top member 212 and the bottom member 214, similar to thatshown in FIG. 14, thereby allowing a user or a reading device to viewthe test strip 270 from both sides thereof.

In some embodiments, a mobile communication device, such as a smartphone, may be used, as disclosed in Ozcan et al., U.S. Pat. No.8,916,390, incorporated herein by reference, to automatically scannedthe test strip 270 via the camera of a smart phone. The scanned imagecan then be interpreted by software to obtain a result and deliver thatresult to a wireless network, for example.

The test device 210 described above with respect to FIGS. 16 through 24may incorporate one or more of the features disclosed in the test device1 described above with respect to FIGS. 1 through 15.

Depending on the analyte being tested and the condition of the fluidspecimen, many of the above embodiments have been found to achieve anaccuracy of at least 99.99%.

In addition, because a result is obtained so quickly, typically within 1minute, the test does not require additional buffers or other methods tohalt the reaction.

Those skilled in the art will readily recognize, in light of and inaccordance with the teachings of the present invention, that any of theforegoing steps may be suitably replaced, reordered, removed andadditional steps may be inserted depending upon the needs of theparticular application. Moreover, the prescribed method steps of theforegoing embodiments may be implemented using any physical and/orhardware system that those skilled in the art will readily know issuitable in light of the foregoing teachings. Thus, the presentinvention is not limited to any particular tangible means ofimplementation.

All the features disclosed in this specification, including anyaccompanying abstract and drawings, may be replaced by alternativefeatures serving the same, equivalent or similar purpose, unlessexpressly stated otherwise. Thus, unless expressly stated otherwise,each feature disclosed is one example only of a generic series ofequivalent or similar features.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. Therefore, it must be understood that the illustratedembodiments have been set forth only for the purposes of examples andthat they should not be taken as limiting the invention as defined bythe following claims. For example, notwithstanding the fact that theelements of a claim are set forth below in a certain combination, itmust be expressly understood that the invention includes othercombinations of fewer, more or different ones of the disclosed elements.

The words used in this specification to describe the invention and itsvarious embodiments are to be understood not only in the sense of theircommonly defined meanings, but to include by special definition in thisspecification the generic structure, material or acts of which theyrepresent a single species.

The definitions of the words or elements of the following claims are,therefore, defined in this specification to not only include thecombination of elements which are literally set forth. In this sense itis therefore contemplated that an equivalent substitution of two or moreelements may be made for any one of the elements in the claims below orthat a single element may be substituted for two or more elements in aclaim. Although elements may be described above as acting in certaincombinations and even initially claimed as such, it is to be expresslyunderstood that one or more elements from a claimed combination can insome cases be excised from the combination and that the claimedcombination may be directed to a subcombination or variation of asubcombination.

Insubstantial changes from the claimed subject matter as viewed by aperson with ordinary skill in the art, now known or later devised, areexpressly contemplated as being equivalently within the scope of theclaims. Therefore, obvious substitutions now or later known to one withordinary skill in the art are defined to be within the scope of thedefined elements.

The claims are thus to be understood to include what is specificallyillustrated and described above, what is conceptually equivalent, whatcan be obviously substituted and also what incorporates the essentialidea of the invention.

What is claimed is:
 1. A device for testing a liquid sample for theconcentration of at least one analyte, comprising: a top member; abottom member connecting to the top member forming an internal cavitytherein; a fluid directing channel formed in the internal cavity; aninlet formed in a first end of the device, the inlet fluidlycommunicating with the fluid directing channel; a press pad formed inthe top member adapted to align with a conjugate color pad of a teststrip, the press pad configured to deflect downwardly and press againstthe conjugate color pad of the test strip disposed within the internalcavity; and a cap fitting over the first end of the device, the capconfigured to press against a fluid collector having the liquid sampledisposed therein, thereby driving the fluid sample into the fluiddirecting channel.
 2. The device of claim 1, further comprising sidewalls disposed from the top member and the bottom member, the side wallsdefining sides of the fluid directing channel.
 3. The device of claim 1,further comprising a plurality of side bars extending along the bottommember, the plurality of side bars forming at least one strip slotconfigured to retain the test strip therein.
 4. The device of claim 3,wherein three strip slots are formed by the plurality of side bars. 5.The device of claim 1, further comprising a result window formed in atleast one of the top member and the bottom member.
 6. The device ofclaim 1, wherein the cap includes a squeezing portion and a specimenretention portion.
 7. The device of claim 6, wherein an interior of thecap includes at least one ramp directing a first portion of a specimeninto the device and a second portion of the specimen into the specimenretention portion.
 8. A test system for testing a liquid sample for theconcentration of at least one analyte, comprising: at least one teststrip comprising: a conjugate color pad including a source ofmobilizable labeled first affinity binding members bindable to theanalyte; a liquid permeable reaction region including at least one stripline including immobilized second affinity capture binding membersbindable to said analyte; and a strip press pad aligned with anddisposed over the conjugate color pad; and a test device comprising: atop member; a bottom member connecting to the top member forming aninternal cavity therein; a fluid directing channel formed in theinternal cavity containing the test strip; an inlet formed in a firstend of the device, the inlet fluidly communicating with the fluiddirecting channel; a press pad formed in the top member, the press padconfigured to press against the strip press pad and the conjugate colorpad of the test strip; and a cap fitting over the first end of thedevice, the cap configured to press against a fluid collector having theliquid sample disposed therein, thereby driving the fluid sample intothe fluid directing channel.
 9. The system of claim 8, furthercomprising side walls disposed from the top member and the bottommember, the side walls defining sides of the fluid directing channel.10. The system of claim 8, further comprising a plurality of side barsextending along the bottom member, the plurality of side bars forming atleast one strip slot configured to retain the test strip therein. 11.The system of claim 10, wherein three strip slots are formed by theplurality of side bars.
 12. The system of claim 8, further comprising aresult window formed in at least one of the top member and the bottommember.
 13. The system of claim 8, wherein the cap includes a squeezingportion and a specimen retention portion.
 14. The system of claim 13,wherein an interior of the cap includes at least one ramp directing afirst portion of a specimen into the device and a second portion of thespecimen into the specimen retention portion.
 15. The system of claim 8,wherein, when the cap is slid onto the test device, the top member andbottom member deforms to cause the press pad of the top member to exerta further force on the strip press pad and the conjugate color pad. 16.A method for testing for an analyte in a sample, comprising: disposingat least one test strip into an internal cavity formed between a topmember and a bottom member of a test device; sliding a cap onto a firstend of the test device to compress a fluid collector to cause the sampleto be expelled from the fluid collector into a fluid directing channelformed in the internal cavity; directing the fluid from the fluiddirecting channel to a conjugate color pad of the test strip, theconjugate color pad aligned with and disposed on a press pad of the topmember; and exerting an additional force on the conjugate color pad ofthe test strip as the cap is slid further onto the first end of the testdevice.
 17. The method of claim 16, wherein the test strip includes atest strip press pad and wherein the press pad of the top member pressesagainst the test strip press pad as the cap is slid onto the first endof the test device.
 18. The method of claim 16, further comprisingreading results on the test strip through a result window formed in atleast one of the top member and the bottom member.
 19. The method ofclaim 16, further comprising compressing the fluid collector bysqueezing a squeezing portion of the cap.